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Old 05-24-2020, 11:29 AM   #32 (permalink)
Aero Wannabe
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Join Date: Dec 2007
Location: NW Colo
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TDi - '04 VW Golf
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Originally Posted by mwebb View Post
EGR is good
more EGR is better than less to a point and defeating a properly function ing EGR does not improve fuel economy or power as
EGR does not operate at high load anyway .

carbon buildup is mostly caused by the driver and bad gas
This has not been my experience and is counter to everything I have read about making Diesel engines run better (although perhaps with higher emissions).

This thread is about driving for mpg which means long periods of low load. This is the type of condition that caused carbon buildup for me in the past. After the tune, which defeats EGR after warmup, my Italian tuneups to blow out carbon are needed much less frequently and show much less carbon when I do.

Also, remember Dieselgate? The cars that VW allowed to cheat the US EPA test performed worse in power and mpg after the VW fix. They cleaned up emissions by calling for more high pressure and low pressure EGR. We had an A3 TDI “Clean Diesel” in the fleet. Even in the factory cheat tune it never came close to the mpg I could get out of the PD TDI.

There is one instance where EGR may help mpg and that is during cold starts. My friend has an 02 TDI and did an EGR delete. This removed the EGR cooler so the exhaust gas no longer warms the coolant on startup. It takes time and a few hard pulls before he gets much cabin heat. FWIW I did not remove the EGR cooler in my TDI for that reason.
60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun

Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.

Last edited by COcyclist; 05-25-2020 at 11:57 PM..
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